The invention relates to novel selenyl- and telluryl derivatives of steroids and to methods for the preparation of these compounds, as well as to the application of such compounds, labelled with radioactive selenium and tellurium isotopes, in diagnostic compositions in particular to be used with a method for diagnostic investigation into abnormalities of internal organs, viz. of the adrenal gland and with a radio-immunologic determination of the steroid-level in the blood or the urine.
For the diagnostic investigation into abnormalities of internal organs, viz. the adrenal gland, according to the so-called "scintigraphic" methods, use has been made already of 19-iodocholesterol labelled with iodine-isotopes .sup.125 I and .sup.131 I that after intravenous administration is found to accumulate itself sufficiently in the adrenal gland so as to be able to make a "scintigram" of it (See the publications by W. H. Beierwaltes, R. E. Counsel et al in J. Nucl. Med. 12, No. 4 (1971), 176, J. Am. Med. Assoc. 216, No. 2 (1971), 275, J. Clin. Endocrin. and Metab. 33 (1971), 713 and J. Nucl. Med. 14, No. 11 (1973), 777).
A drawback of working with this radio-actively labelled 19-iodocholesterol is for instance the high irradiation load, viz. the thyroid gland being overloaded (see J. Nucl. Med. 14, No. 9 (1973), 713) and the poor stability of the compound, both in vivo and in vitro (see J. Nucl. Med. 15, No. 1 (1974), 38).